Method for stem sample inspection in a charged particle beam instrument

ABSTRACT

A method for sample examination in a dual-beam FIB calculates a first angle as a function of second, third and fourth angles defined by the geometry of the FIB and the tilt of the specimen stage. A fifth angle is calculated as a function of the stated angles, where the fifth angle is the angle between the long axis of an excised sample and the projection of the axis of the probe shaft onto the X-Y plane. The specimen stage is rotated by the calculated fifth angle, followed by attachment to the probe tip and lift-out. The sample may then be positioned perpendicular to the axis of the FIB electron beam for STEM analysis by rotation of the probe shaft through the first angle.

CLAIM FOR PRIORITY

The present application is a divisional of application Ser. No.12/041,217, filed Mar. 3, 2008, which application claims the priority ofU.S. provisional application Ser. No. 60/925,762, filed Apr. 23, 2007and titled “Method and Apparatus for Cassette-Based In-Situ STEM SampleInspection;” all of which foregoing applications are incorporated byreference into the present application.

TECHNICAL FIELD

This application relates to TEM sample preparation and inspection insidea charged-particle instrument, such as a dual-beam focused-ion beammicroscope, called a “DB-FIB” in this application.

BACKGROUND

The use of focused ion-beam (FIB) microscopes has become common for thepreparation of specimens for later analysis in a transmission electronmicroscope (TEM) or scanning transmission electron microscope (STEM),and the in-situ lift-out technique has become the method of choice forthe preparation of a tiny sample for TEM inspection. TEM and STEMinspection offer fine image resolution (<0.1 nm), but requireelectron-transparent (<100 nm thick) sections of the sample. TEM andSTEM inspection usually take place in a separate TEM or STEM device,which requires the transfer of a fragile TEM sample to another location.Dual-beam (DB-FIB) instruments are being more widely used for TEM samplepreparation and inspection. The DB-FIB instrument combines highresolution imaging of the SEM with precision, site-specific ion millingof the FIB. The combination of SEM and FIB in the same chamber allowsfor the location, preparation and inspection of samples in the samemicroscope. The electron beam within the DB-FIB can substitute for aconventional STEM beam, and a transmitted electron detector, locatedbeneath the sample in the DB-FIB enables in-situ STEM imaging of asample. As a result, this system provides an increased throughput atreduced cost per sample for failure analysis and process controlapplications requiring STEM analysis. Applying in-situ lift-outtechnology in the DB-FIB provides a means for excising tiny samples froma specimen and positioning them on TEM sample holder or grid, using thespecial features of a nano-manipulator device, for later inspectionwithin the DB-FIB. A suitable nano-manipulator system is the OmniprobeAutoProbe 200™, manufactured by Omniprobe, Inc., of Dallas, Tex.

DRAWINGS

FIG. 1 shows a perspective view of a selectively thinned TEM sample, cutfree, but still sitting in its cavity within a specimen.

FIG. 2 shows a side view of a DB-FIB system with a TEM sample lifted outof a specimen. For clarity, only the e-beam column is shown.

FIG. 3 shows the perspective view of a DB-FIB system with a TEM samplelifted out of the specimen (both e-beam and ion beam columns shown).

FIG. 4 shows a perspective view of a DB-FIB system with a TEM samplelifted out of a specimen. The specimen is shown thinned and partiallyrotated about the nano-manipulator shaft axis (only e-beam column isshown).

FIG. 5 shows a perspective view of a DB-FIB system with a TEM samplerotated and oriented for STEM analysis (both e-beam and ion beam columnsshown).

FIG. 6 shows a side view of a DB-FIB system with a TEM sample rotatedand oriented for STEM analysis (both e-beam and ion beam columns shown).

FIG. 7 shows a side view of a DB-FIB system with the specimen stagereturned into a horizontal orientation and lowered, a TEM sample readyfor STEM analysis, and a transmitted electron detector moved intoposition.

FIG. 8 shows a plan view of the horizontal plane through the sampleposition with the axis of the electron beam column normal to the page,and depicting the angular position of the nano-manipulator probe shaftabout the electron beam axis and relative to the stage tilt axis that isperpendicular to the ion beam axis.

FIG. 9 shows a perspective view of a cassette containing collared probetips with TEM samples attached.

FIG. 10 shows a perspective view of a cassette containing collared probetips with TEM samples attached. The cassette is shown mounted on acassette holder.

FIG. 11 shows a perspective view of a cassette holding collared probetips with TEM samples attached. One of the tips shown is held by thegripper of a nano-manipulator. The cassette is shown mounted on acassette holder.

FIG. 12 shows a perspective view of a cassette containing the collaredprobe tips with TEM samples attached, where the collared probe tips arekept by wire forms. Different embodiments of collars are shown.

FIG. 13 shows a perspective view of a cassette holding probe tipswithout collars, where the collars are held in place by a spring means.

FIG. 14 shows a perspective view of two cassettes connected to asubstage of a specimen stage.

FIG. 15 is a flowchart depicting methods according to the preferredembodiment.

FIG. 16 shows the perspective view of the system according to anotherembodiment, where the system includes the laser apparatus and a gasinjector.

DESCRIPTION

We describe a novel method and apparatus for the process of location,preparation and inspection of samples (120) inside a dual-beam FIBmicroscope (DB-FIB) using an in-situ probe tip replacement system and acassette (200) for holding these samples (120). The field of applicationis not limited to an in-situ probe tip replacement system, dual-beam FIBsystems, or to semiconductor samples; applications could include, forexample, nano-mechanical systems or biological samples.

The method and apparatus of this application provide for higherthroughput STEM inspection within the DB-FIB, because the sample doesnot have to be removed from the microscope. As shown in FIG. 1, thein-situ lift-out process begins in the conventional manner, in which asample pre-form (122) is excised from the specimen (160) by ion-beam(190) milling. Such milling may also be performed in particular cases bymilling with the electron beam (100) or a laser beam (180) (FIG. 16),with or without assistance from a gas injector (185) (FIG. 16). Thespecimen stage (170) is tilted to allow a cut around the sample pre-form(122), preferably in a U-shape, and then tilted at another angle for anundercut to free the sample (120). Then, the stage (170) is furthertranslated and rotated to a calculated position for lift-out, asexplained below. FIG. 1 shows the stage positioned for milling aroundthe sample pre-form (122), where the tilt axis (175) of the stage (170)is collinear with the long axis (123) of the sample (120). The probe tip(130) may be connected to the released lift-out sample (120) using oneof the methods disclosed in U.S. Pat. No. 6,570,170, for example. Afterreorientation, the sample (120) is then lifted out and disposed at anangle allowing STEM analysis as described in the following disclosure.In all the figures, the size of a sample (120) is exaggerated forclarity.

Method

FIGS. 1-5 show the several stages of lift-out and positioning. Followingpartial thinning, the released lift-out sample (120) can be manipulatedto allow immediate inspection of the area (125) of interest by thee-beam (100) and a transmitted electron detector (210). Obtaining theproper orientation of the sample (120) is aided by a feature typical ofDB-FIB sample stages (170) that allows the stage (170) to rotate, tilt,and translate in X, Y, and Z-axes. The sample (120) is cut loose fromthe specimen, and then the specimen stage (170) is tilted and rotated,as described below. The sample (120) is removed from its trench (121) bythe nano-manipulator (140), and after the nano-manipulator shaft isrotated, the sample (120) will have an orientation sufficientlyperpendicular to the electron beam (100) axis (105) to be suitable forSTEM analysis in the DB-FIB. (Typically the electron beam (100) axis(105) is vertical in the DB-FIB.) If necessary, the sample (120) can beadditionally thinned after the lift-out procedure.

Table 1 below shows the mathematical transformations that may be used todetermine the correct angles for the DB-FIB sample stage (170) rotationand tilt required to orient the sample (120) for the operationsdescribed below. The exemplary calculations shown in Table 1 are a novelapplication of the well-known conversion from angle-axis representationto rotation-matrix representation. The reader may consult Craig, JohnJ., “Introduction to Robotics Mechanics & Control,” Addison-WesleyPublishing Co., 1986, pp. 322-321, for details.

In Table 1, the location of the nano-manipulator probe shaft (110) inthe DB-FIB chamber is expressed in terms of a first angle, representinga rotation of the nano-manipulator probe shaft (110) (Θ₁ in thefigures); a second angle, being the angle of the stage (170) tiltrelative to the X-Y horizontal plane (165) (Θ₂ in the figures); a thirdangle, being the angle between the projection in the X-Y plane (165) ofthe axis (115) of the nano-manipulator probe shaft (110) and theextension of the stage (170) tilt axis (175) nearest the front door(135) of the DB-FIB. (Θ₃ in FIG. 8); a fourth angle being the angle ofinclination of the axis (115) of the shaft (110) of the nano-manipulator(140) relative to the X-Y horizontal plane (165) of the DB-FIB (Θ₄ inthe figures); and a fifth angle, being the angle between the projectionin the X-Y plane (165) of the of the axis (115) of the probe shaft (110)and the long axis (123) of the sample (120) (Θ₅ in FIG. 8), asdetermined by the location of the sample (120) and the rotation of thestage (170). If the sample (120) is initially in the position “A” inFIG. 8, then rotation of the stage (170) by Θ₅ will place the sample(120) in the desired position “B” for lift-out. The angle Θ₁ is taken tobe zero when the probe shaft (110) is at the position of the sample(120) at lift out. The angle Θ₅ is taken to be zero along the long axis(123) of the sample (120); Θ₂ is taken to be zero when the stage ishorizontal with respect to the X-Y plane (165). If the stage (170) hasmore than one tilt axis, then the relevant tilt axis (175) is thatsubstantially perpendicular to the axis (195) of the ion beam (190).

We have found it convenient to use the following values for the anglesdescribed above for a Model 1540 Cross-Beam DB-FIB, manufactured by CarlZeiss, Inc.:

-   -   Θ₂=0° (for stage tilt),    -   Θ₃=140° (relative to the extension of the stage tilt axis        nearest the front door of the DB-FIB),    -   Θ₄=26.5° (for inclination of the probe shaft axis relative to        DB-FIB X-Y plane).

Thus resulting in the following computed values as shown in Table 1below:

-   -   Θ₁=104.4° (for desired probe shaft rotation)    -   Θ₅=10.1° (for desired stage rotation).

TABLE 1 Compute the rotation matrix of coordinates about axis of probeshaft through angle θ₁, where the components of the vector representingthe axis of the probe shaft are as follows (assuming unit vectors):$\begin{matrix}{k_{x} = {\cos\;{\theta_{3} \cdot \cos}\;\theta_{4}}} & {k_{y} = {\sin\;{\theta_{3} \cdot \cos}\;\theta_{4}}} & {k_{z} = {\sin\;\theta_{4}}} & {V = {1 - {\cos\;\theta_{1}}}}\end{matrix}$ The following exemplary angles are predetermined: θ₂ = 0;θ₃ = −140 deg.; θ₄ = 26.5 deg. The rotation matrix for rotation aboutthe probe shaft is therefore: $\begin{matrix}\; & {{k_{x}^{2} \cdot V} + {\cos\;\theta_{1}}} & {{k_{x} \cdot k_{y} \cdot V} - {{k_{z} \cdot \sin}\;\theta_{1}}} & {{k_{x} \cdot k_{z} \cdot V} + {{k_{y} \cdot \sin}\;\theta_{1}}} \\{{{Rot}\;\theta_{1}} =} & {{k_{x} \cdot k_{y} \cdot V} + {{k_{z} \cdot \sin}\;\theta_{1}}} & {{k_{y}^{2} \cdot V} + {\cos\;\theta_{1}}} & {{k_{y} \cdot k_{z} \cdot V} - {{k_{x} \cdot \sin}\;\theta_{1}}} \\\; & {{k_{x} \cdot k_{z} \cdot V} - {{k_{y} \cdot \sin}\;\theta_{1}}} & {{k_{y} \cdot k_{z} \cdot V} + {{k_{x} \cdot \sin}\;\theta_{1}}} & {{k_{z}^{2} \cdot V} + {\cos\;\theta_{1}}}\end{matrix}\quad$ The rotation matrices for rotation about the X-axis(θ₂) and the Y-axis (θ₅) are: $\begin{matrix}\; & 1 & 0 & 0 & \; & {\cos\;\theta_{5}} & {{- \sin}\;\theta_{5}} & 0 \\{{{Rot}\;\theta_{2}} =} & 0 & {\cos\;\theta_{2}} & {{- \sin}\;\theta_{2}} & {{{Rot}\;\theta_{5}} =} & {\sin\;\theta_{5}} & {\cos\;\theta_{5}} & 0 \\\; & 0 & {\sin\;\theta_{2}} & {\cos\;\theta} & \; & 0 & 0 & 1\end{matrix}\quad$ Compute a product matrix, T = Rotθ₁ · Rotθ₂ · Rot θ₅θ₁ is determined by the element 2,2 (index origin zero) in the matrix Twhen T = 0, that is, when: cosθ₂ · [cosθ₁ + sinθ₄ ² · (1-cosθ₁)] − sinθ₂· [cosθ₃ · cosθ₄ · sinθ1 + cosθ₄ · sinθ₃ · sinθ₄ · (1 - cosθ1)] = 0.Since θ₃ and θ₄ are predetermined, a solution for θ₁ for the exemplaryvalues given is: θ₁ = 104.394 deg. Since θ₁ is now known, element 1,1 ofT solves for θ₅ when T = 0, that is: cosθ₅ · [sinθ₂ · [cosθ₃ · cosθ₄ ·sinθ₁ − cosθ₄ · sinθ₃ · sinθ₄ · (1-cosθ₁)] − cosθ₂ · [cosθ₁ + (cosθ₄ ·sinθ₃ ² · (1-cosθ₁)]] − sinθ₅ · [sinθ₄ · sinθ₁ + cosθ₃ · (cosθ₄)² ·sinθ₃ · (1-cosθ₁)] = 0. Again, since θ₃ and θ₄ are predetermined, asolution for θ₅ for the exemplary values given is: θ₅ = 10.094 deg.

The angle Θ₁ is a function of Θ₂-Θ₄, and Θ₅ is a function of Θ₁-Θ₄. So,in this example, given a stage (170) tilt angle of 0°, and a probe shaftinclination of 26.5°, a stage (170) rotation of approximately 10.1° willorient the sample (120), so that the sample (120), after lift-out, canbe made substantially perpendicular to the vertical electron beam (100)simply by rotating the nano-manipulator probe shaft (110) by 104.4° (Θ₁in the figures). FIGS. 2 and 3 show the attachment of the probe tip(130) to the sample (120), after the stage (170) has been rotated by Θ₅,followed by lift-out. FIGS. 4-6 show the rotation of the sample (120)attached to the probe tip (130) by Θ₁. FIG. 6 is a side view of thesample (120) rotated into the desired orientation.

The reader should understand that the angles stated above for Θ₂, Θ₃,and Θ₄ are exemplary only for the model of DB-FIB stated, and otherangles could be used as input to the procedures set out in Table 1 tocalculate the rotation of the nano-manipulator shaft (110) required tobring the sample (120) into the proper orientation for STEM imaging,both for the Zeiss DB-FIB, and instruments of other manufacturers. Thepre-determined angles most convenient for a particular DB-FIB can beeasily determined from the construction of the particular DB-FIB. ThusΘ₂, the stage tilt is conveniently set to zero; and Θ₃, the projectionof the axis (115) of the probe shaft (110) relative to the axis (175) ofthe tilt of the stage (170), and Θ₄, the inclination of the probe shaft(110) are determined by the location of the probe port and its anglewith respect to the X-Y plane on the particular DB-FIB.

These calculations and operations to orient the sample stage (170) andthe probe shaft (110) are preferably carried out by a programmablecomputer connected to suitable actuators, as described in the patentapplications incorporated by reference into this application. Computercontrol of motors or actuators inside FIB instruments is known in theart.

As shown in FIG. 7, a conventional transmitted electron detector (210)may be positioned and exposed in an appropriate position beneath thesample (120), so that the sample (120) can be imaged immediately in STEMmode. The position and aperture of the STEM detector (210) can beadjusted to select bright field or dark field imaging modes.

As shown in FIGS. 9-13, the sample (120) attached to thenano-manipulator probe tip (130) can be deposited into a cassette (200)located within the DB-FIB, thus enhancing its stability and allowingflexibility in positioning. The cassette (200) is typically located onthe specimen stage (170) of the DB-FIB. The sample (120) is held in avery stable mechanical condition, because it is attached to the probetip (130) when placed into the cassette (200). The position of thesample (120) in the cassette under the electron beam (100) is determinedby the tilt, rotation, and X, Y and Z position of the DB-FIB specimenstage (170) at lift-out followed by the rotation of the nano-manipulatorshaft, as described above, and by an additional axis of tilt of thecassette (200), if any. Therefore, the cassette (200), by having oneaxis of tilt normal to the DB-FIB stage (170) tilt axis (175), canprovide for two essentially orthogonal tilt axes, thereby enabling anytilt orientation of the sample (120) under the electron beam (100). Thisdual axis tilt is preferable to, for example, a “flip stage”configuration in which only one degree of tilt is available from theDB-FIB stage (170). Tilt of the sample (120) in two degrees of freedomis often critical for obtaining the desired contrast in the STEM image.Obtaining the desired contrast in the STEM image while the sample (120)is in the DB-FIB may eliminate the need to take the sample (120) to aseparate TEM or STEM instrument for inspection.

The Cassette

The cassette (200) disclosed comprises a cassette base (230) and one ormore probe tip stations (220, 221). The cassette (200), as depicted inFIG. 9, comprises two probe-tip stations (220), but the number ofprobe-tip stations (220) is not limited to two. In the embodiment shownin FIG. 9, each probe-tip station (220) comprises an insert part (240),so that the insert part (240) and the base (230) together define acollar cavity (265), for receiving a probe tip collar (300); a firstcutout (255) for the shaft of the probe tip; a probe tip slot (270), forreceiving the shaft of the probe tip (130); and a second cutout (256)for the probe tip (130) itself. The insert parts (240) and the base(230) are shown held by screws (250). This assembly also defines adivider portion (245) of the base (230) with the first cutout (255) init.

FIGS. 10 and 11 show a cassette (200) connected to a cassette holder(275) by a second screw (251). In FIGS. 10 and 11, the cassette holder(275) is shown attached to a substage (280) of the specimen stage (170)that is typical of the Zeiss Model 1540 instrument referred to above.Preferably, the substage (280) has nests (205) for receiving andstabilizing the cassette (200). The angle of the probe tip slot (270)relative to the plane of the cassette holder (275) is Θ₄, the same asthe angle of the probe shaft (110) relative the DB-FIB X-Y plane. (Theplane of the cassette holder (275) is parallel to the substage (280).)This geometry assures that the orientation of the sample (120) whenplaced in the probe tip slot (270) is the same as that resulting afterthe sample (120) is rotated according to the calculations discussedabove. The angle Θ₄ is shown in FIG. 10, but omitted in the otherfigures for clarity.

To ensure the stability of the probe tip (130) in the probe tip slot(270), a tape or film (260) with adhesive is preferably attached to thedivider portion (245) to releasably capture the probe tip collar (300).A suitable material for the tape (260) is KAPTON film, with acrylic orsilicone adhesive layers on both sides, available from the DuPontCorporation. The tape (260) is consumable and requires periodicreplacement. The particular embodiment shown in FIG. 9 shows a probe tip(130) having a collar (300) attached to it, to ease the capture of aprobe tip (130) once it is placed in the probe tip slot (270), and thecollar (300) is placed in the collar cavity (265). The collar (300) canbe of simple cylindrical shape or can have particular cutouts or grooves(310) in this cylindrical part (FIG. 12).

To load the probe tip (130) into a cassette probe-tip station (220), theprobe tip (130), with sample (120) attached and releasably held by thegripper (150) on the probe shaft (110), is maneuvered to the vicinity ofthe cassette (200) by the nano-manipulator (140). The cassette (200) ismounted on the specimen stage (170) or a substage (280) in a position,so that the probe tip slot (270) is oriented at the correct anglerelative to the specimen (160) surface. The probe tip (130) is moved tothe probe tip slot (270) until the collar (300) is located exactly abovethe collar cavity (265) in the probe tip station (220). Then the probetip (130) is lowered so the collar (300) is placed entirely inside thecollar cavity (265). The nano-manipulator (140) continues moving alongthe probe tip (130) axis (115) so the collar (300) contacts the adhesivetape (260) and stays attached to it while the nano-manipulator (140)continues its movement, disengaging the gripper (150) from the probe tip(130). This situation is depicted in FIG. 11, where the probe tip (130)in a first probe-tip station (220) was placed in the probe tip slot(270) earlier and remains attached to the adhesive tape (260). The probetip (130) in a second probe-tip station (221) is in the process of beingplaced in the probe tip slot (270). There are openings (285) in thecassette holder (275), located beneath the sample (120), to allow theimmediate in-situ STEM analysis.

FIGS. 12 and 13 show a spring means (290), such as springy wire forms orleaf springs, used to capture the probe tip (130) inside the probe tipstation (220). FIG. 12 shows the spring means (290) used to hold theprobe tip (130) with a collar (300). FIG. 13 shows another embodimentwhere the spring means (290) holds a probe tip (130) without collars.

FIG. 14 shows another embodiment where the two cassettes (200) areplaced into a different nest (206) attached to a different embodiment ofa substage (281) for conveniently holding multiple cassettes (200). Anoptional sample puck (330) functions as relocatable support forspecimens (320). This type of substage is typical of instrumentsmanufactured by the FEI Company of Hillsboro, Oreg. The substage (281)shown in FIG. 14 is mounted on the FIB stage (170). This arrangementallows an additional angle of tilt of the cassette (200) (and thus thesample (120)). In FIG. 14, the substage (281) has an axis (225) of tiltsubstantially orthogonal to the axis of tilt (175) of the specimen stage(170). The two axes (175, 225) need not be orthogonal, but thiscondition simplifies the movements and calculations needed to bring thesample (120) into a desired viewing position. In other embodiments, thedesired tilt of the cassette (200) may be obtained by tilting thecassette holder (275) relative to the substage (281), or, if thecassette holder (275) is attached to the specimen stage (170) itself,relative to the stage. Tilt of the substage (281) or the cassette holder(275) may be accomplished by motors or other actuators (not shown), asis known in the art for motion control inside FIB instruments.

In-situ STEM Process Flow

FIG. 15 shows a flowchart of the method of the preferred embodiment. Itstarts with the system setup step 340, including the setup of theDB-FIB, nano-manipulator (140), cassette (200) and all other necessaryaccessories, and the location of an area of interest on the specimen(160). In step 341, the TEM lift-out sample (120) is excised from thespecimen (160), thinned for STEM or TEM inspection, and released fromthe specimen (160). In step 342, the first and the fifth angles arecalculated as described above. In step 343, the specimen stage (170) isadjusted (translated, tilted or rotated) to a position and angle asdescribed above that will later permit the thinned portion (125) of theTEM sample to be placed perpendicular to the electron beam by a singlerotation of the nano-manipulator probe shaft (110). In step 344, theprobe tip (130) is attached to the pre-thinned and released sample (120)and the sample (120) is lifted-out.

In an alternative procedure, the TEM lift-out sample (120) can beexcised from the specimen (160) without selective thinning to produce anelectron transparent portion (125). The selective thinning can be laterperformed after the TEM sample (120) has been lifted out of its trench(121).

Step 341 is depicted in FIG. 1. In FIG. 1, the selectively thinned TEMsample pre-form (122) is shown cut free but remaining in its trench(121) in the specimen (160). In FIG. 2, the sample (120) is lifted outof its trench (121) and is held by the nano-manipulator (140) above thespecimen stage (170). For clarity, only the electron beam (100) isshown. In FIG. 3, the perspective view of the same configuration as inFIG. 1 is shown, with both electron (100) and ion (190) beams shown.Step 345 reflects the rotation of the nano-manipulator shaft (110)through the first angle as calculated in step 342. This step is depictedin FIGS. 4 through 6. In FIG. 4, the side view of the next step of anano-manipulator shaft (110) rotation is shown. FIG. 5 shows thefollowing step of the preferred embodiment where the sample (120) ispositioned perpendicular to the electron beam (100) so the thinned area(125) of interest can be STEM inspected. In FIG. 5, both electron (100)and ion beam (190) columns are shown. FIG. 6 shows the side view of thesame sample (120) orientation.

A decision may be made at step 346 either to perform an immediate orpreliminary STEM analysis or to place the probe tip (130) with the TEMsample (120) attached, into the cassette (200). If the decision is toperform the immediate STEM analysis, the process continues in steps 353through 358 followed by the transfer of the TEM sample (120) attached toa TEM grid (not shown) outside the FIB (step 365). FIG. 7 shows thefinal configuration with the sample (120) oriented perpendicularly tothe electron beam (100), specimen stage (170) lowered and thetransmitted electron detector (210) moved in. FIG. 8 shows a plan viewfrom the top of the charged particle beam apparatus. The electron beam(100) is oriented vertically to the plane of the view.

After the preliminary STEM in-situ analysis on the TEM sample (120),attached to the probe tip (130), held by the nano-manipulator (140), hasbeen performed in step 354, a decision may be made in step 355 tocontinue the in-situ procedure, and to proceed with the additional STEManalysis on a TEM sample (120). In step 356, the TEM sample (120) isattached to a TEM sample grid, located elsewhere on the specimen stage(170), using material deposition in the DB-FIB or other methods known inthe art, followed with the separation of the probe tip (130) from theTEM sample (120) in the step 357. The additional in-situ STEM analysisof the TEM sample (120) can be performed in step 358, followed with thetransfer of the TEM sample (120) attached to the TEM sample grid,outside the FIB in step 365.

Alternatively, in step 355 the decision can be made not to performadditional in-situ STEM analysis. In this case, in step 347, the probetip (130) with the TEM sample (120) attached to it is deposited into acassette (200) for further procedures.

Or, if the other decision has been made in step 346, the probe tip (130)can be placed into the cassette (200) immediately at step 347. Then, inthe step 348, the choice is made whether to continue with the lift-outprocedure for another sample (in this case the process would continue atthe initial step 340), or to proceed to STEM analysis of samples (120)already placed into a cassette (200) in step 349. The specimen stage(170) is manipulated accordingly (lowered or raised) in step 349 and thein-situ STEM analysis of one or more samples is performed in step 350.The image obtained is checked for quality in step 351. If the quality isnot satisfactory, the TEM sample (120) can be re-thinned tilting thestage (170) and/or the cassette (200) to the desired orientation (step352).

After a satisfactory quality image is obtained, the process can becontinued in step 359 with the choice to perform TEM analysis in aseparate, standalone TEM or STEM instrument. If the choice is “No,” thecassette (200) is transferred outside the DB-FIB for any necessaryfurther procedures (step 365). If the choice is “Yes,” then in step 360the probe tip (130) with the TEM sample (120) attached to it is capturedagain with the gripper (150) and returned to its original orientation instep 361 using rotation of the probe shaft (110) as described above,followed with the adjustment of the TEM grid orientation in step 362.Then in step 363 the TEM sample (120) can be attached to the TEM gridusing material deposition in the DB-FIB, or other conventional methods,followed with the separation of the probe tip (130) from the TEM sample(120) in step 364. Thereafter, the TEM grid with the TEM samplesattached to it can be transferred outside the DB-FIB for furtherinvestigation in step 365.

This embodiment comprises a set of repeated operations and isappropriate for an automated procedure. It can be the part of theprobe-tip exchange procedure described in co-pending U.S. patentapplication Ser. No. 11/186,073, which in turn is the part of theautomated lift-out procedure described in the co-pending automatedlift-out procedure (U.S. application Ser. No. 11/265,934). The methoddescribed is not limited to DB-FIB instruments with a fixed relationshipbetween the electron (100) and ion (190) beam columns. The method can bepracticed on an instrument with the ability to tilt one or both beamsrelative to the specimen stage (170).

The method described can be also used in an apparatus for lift-out wherea laser beam (180) is used in addition to or instead of the ion beam. Anembodiment is shown in FIG. 16, where the laser beam (180) and the gasinjector apparatus (185) are schematically shown. In this embodiment,the laser beam (180) is used to pre-cut the sample (120) from the waferpossibly using gas chemistries provided by the gas injector (185) andpossibly using a mask (not shown) followed by thinning performed by ionbeam (190). The laser beam (180) and the ion beam (190) may reside inthe same chamber or in separate chambers.

Since those skilled in the art can modify the specific embodimentsdescribed above, we intend that the claims be interpreted to cover suchmodifications and equivalents.

1. A method for examination of an excised sample in a charged particlebeam instrument, where the sample has a long axis, and where the chargedparticle beam instrument comprises: an ion-beam; a specimen stage; thespecimen stage having at least one tilt axis substantially perpendicularto the axis of the ion beam; an electron beam; the electron beam havingan axis; and, an X-Y plane; a nano-manipulator; the nano-manipulatorhaving a probe shaft; the probe shaft having an axis; the probe shaftfurther having a probe tip; a cassette for holding probe tips; thecassette having at least one probe tip-station for receiving a probetip; each probe-tip station capable of receiving a probe tip at an anglefrom the X-Y plane of the charged particle beam instrument equal to apre-determined fourth angle; where the method comprises: calculating afirst angle as a function of: a pre-determined second angle that is theangle of tilt of the specimen stage relative to the X-Y plane of thecharged particle beam instrument; a pre-determined third angle that isthe angle between the tilt axis of the specimen stage and the projectiononto the X-Y plane of the axis of the probe shaft; and, thepre-determined fourth angle that is the inclination of the axis of theprobe shaft relative to the X-Y plane of the charged particle beaminstrument; calculating a fifth angle as a function of the first,second, third, and fourth angles, where the fifth angle is the anglebetween the long axis of the sample and the projection of the axis ofthe probe shaft onto the X-Y plane; rotating the specimen stage to thecalculated fifth angle, whereby the projection of the axis of the probeshaft onto the X-Y plane is collinear with the long axis of the sample;attaching the sample to the probe tip; lifting out the sample with theprobe tip; rotating the probe shaft by the calculated first angle,whereby the sample is placed substantially perpendicular to the axis ofthe electron beam; and, releasing the probe tip with the sample attachedfrom the probe shaft into the probe-tip station of the cassette, wherebythe sample remains oriented substantially perpendicular to the axis ofthe electron beam.
 2. The method of claim 1 where calculating the firstangle and the fifth angle comprises transforming an angle-axisrepresentation of the first, second, third, fourth and fifth angles to arotation matrix representation.
 3. The method of claim 1, furthercomprising imaging the sample by a transmitted electron detector placedbeneath the cassette.
 4. The method of claim 1, further comprising:carrying out STEM analysis on the sample while the sample is in theprobe-tip station; engaging the probe tip by the nano-manipulator probeshaft; rotating the probe shaft by an angle in the opposite sense of thefirst angle; and, carrying out STEM analysis on the sample.
 5. Themethod of claim 4, further comprising: thinning the sample afterattaching the sample to the TEM grid; carrying out additional STEManalysis on the sample; and, transferring the cassette and sampleoutside the charged particle beam instrument.
 6. The method of claim 1further comprising: transferring the cassette holding the sample outsidethe charged particle beam instrument.
 7. The method of claim 1, wherethe charged particle beam instrument further comprises: a cassetteholder, the cassette holder capable of releasably holding the cassette;the cassette holder having an opening beneath the sample released intothe probe-tip station; the method comprising: moving the cassette holderto a position under the electron beam, so that the electron beam passesthrough the sample and the opening.
 8. The method of claim 7, where thecharged particle beam instrument further comprises a substage; themethod comprising: mounting the cassette holder onto the substage; and,tilting the substage in a direction substantially orthogonal to the tiltaxis of the stage.